fix(markup): adapt button helpers to layer 229 button types

[OCharnyshevich]

Fixes the build of #1850 (layer 229). CI there fails because telegram/message/markup still uses the keyboardButton* constructors that layer 229 removed.

Layer 229 splits buttons into two concrete types: keyboardButton with a ButtonType for reply keyboards, and keyboardInlineButton with an InlineButtonType for inline keyboards. This PR ports the helpers to that model.

API changes

• Helper names are unchanged. Return types follow the new model:
  • tg.KeyboardButton: Button, RequestPhone, RequestGeoLocation, RequestPoll, RequestPeer, SimpleWebView
  • tg.KeyboardInlineButton: URL, Callback, SwitchInline, Game, Buy, URLAuth, InputURLAuth, UserProfile, InputUserProfile, WebView
• New generic helpers KeyboardButton(text, tg.ButtonTypeClass, style...) and InlineButton(text, tg.InlineButtonTypeClass, style...) cover any button type, including ones added later. The named helpers are built on them.
• New helpers for the new inline types: Copy, Disabled.
• New InlineButtonRow. Row/SingleRow take reply buttons; InlineRow, InlineKeyboard and the Row methods in message and message/inline take inline buttons.
• URLAuth and UserProfile were reply-keyboard buttons. Layer 229 only has inline forms, so they are inline now.
• Style options are unchanged.

Code that mixed reply and inline buttons in one row no longer compiles. The protocol no longer allows that either.

Tests

• Split the row tests into inline and reply keyboards.
• Added encode/decode round-trip tests for both keyboard kinds.
• Extended the style tests to Copy and Disabled.

go build ./..., go vet ./telegram/... and go test ./... pass locally on top of #1850.

telegram/message/audio.go is not gofmt-clean on the #1850 branch. I left it out because it's unrelated.

Motivation

We need layer 229 for ephemeral bot messages. On layer 228 the server sends updateEphemeralBotCallbackQuery#9b380762, which is only in _schema/tdlib.tl. gotd can't decode it and drops the whole updates container, so callback buttons on ephemeral messages can't be handled.